The present invention generally relates to a device for cooling a charged piston internal combustion engine having charge air cooling and a coolant recooler, and more particularly to a device which ensures an operation of the piston internal combustion engine which is free of disturbances in the case of alternating loads and environmental conditions.
A device of this type is disclosed by German Patent Application (DE) 21 20 790 B2 which has separate coolant circulating systems for the charge air cooling and for the engine cooling. As a result, the temperatures in the two circulating systems may be selected to differ corresponding to the component requirements without being influenced by one another. However, this object is achieved by additional expenditures with respect to components. Thus, subassemblies, such as a safety device, a control device, a coolant pump, an expansion tank, a filler neck, must be present in both coolant circulating systems and therefore exist twice. These additional components increase the weight, the overall size and the costs of a correspondingly equipped piston internal combustion engine. In addition, the coolant circulating system for the charge air cooling, which is divided into two parallel separately controllable lines between the circulating pump and the charge air cooler, also leads to double expenditures. The control valve of one line is temperature-controlled, and the control valve of the other line is controlled as a function of the charge air pressure.
Therefore, it is an object of the invention to provide a device for the cooling of a charged piston internal combustion engine which, with low expenditures with respect to parts for the device, permits a cooling in all operating ranges which is adapted to the requirements of the components of the piston internal combustion engine.
Advantages achieved by preferred embodiments of the present invention include, in particular, that expenditures with respect to parts for the device are reduced in comparison to the disclosed arrangement, that, despite the mutually communicating circulating-system branches, the lowering of the charge air temperature to the minimum permitted by the coolant recooler is possible without any restriction as a result of the minimum temperature of the coolant at the inlet into the piston internal combustion engine, and that, as a result of the overcontrolling of the change-over device which is a function of the charge air pressure, a control of the coolant circulating system is provided which reacts rapidly to a load increase of the piston internal combustion engine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.